This invention relates to a conveyor belt with an endless or mechanically connected belt band that is guided in a supporting frame around terminally arranged deflection rollers and that has a linear motor system--arranged along the belt band--with stators and magnets that are associated with the belt band.
Such conveyor belts are used above all in underground mine and tunnel construction to transport coal and rocks or ore. They are also used above-ground to convey the most varied materials. These conveyor belts cover considerable distances, although the length of these conveyor systems, in underground mining, will depend on the layout of the roads. For example, if the latter run along a curve or if they are bent at a right angle or some other angle, then transfer devices must be set up at these points and that, to some extent, also entails rather considerable installation and above all attendance efforts. Furthermore, the motors used here represent a limitation in which connection--by including intermediate drives (ZE "Hebezeuge und Fordermittel" 18, 1978 pages 76-80)--an attempt was made to increase the length of the belt conveyors and at the same time also to reduce the stress on that belt band. But it was found that such intermediate drives are not suitable because the necessary friction value between the two belts is not adequately assured. Furthermore, decentrally placed drives have been used in the form of linear motors with the permanent magnets being inserted into the edges of the belt band cover while the electromagnets--then grasping around the edges of the belt band and lying in stators--were driven in the form of a linear motor drive. The experiments were discontinued because, first of all, the forces acting upon the two edges of the belt band were not uniform and, besides, because the stators were slightly damaged by the conveyor belt. Moreover, dust settles in the gap between stator and conveyor belt so that there is no longer any necessary magnetic force flux.
DE-OS 37 41 054 reveals conveyor belts with linear drives, where the permanent magnets are integrated into a guide bar placed upon the underside of the belt band. The stators are arranged laterally and so as to act upon the permanent magnets, next to the drive or guide bar. In addition to these drives, there are also provided lifting devices in the form of permanent magnets and stators, whereby the permanent magnets are housed in the edges of the conveyor belt and the stators are provided perpendicularly on top. These linear motors are used to try to lift the belt so that the carrying rollers actually only perform guidance functions because the belt practically floats on the magnetic force cushion. The conveyor belt, with integrated permanent magnets, must be guided at the end of the belt band conveyor around deflection rollers; this naturally generates stress and tumbling processes that severely impair these parts of the linear motor drive. The lifting of the belt is not adequate either so that--especially in the middle, where the conveyor belt is loaded by the material to be conveyed--powerful tumbling work is again generated on the belt band rollers so that such a belt or such a belt band will reveal a heavily restricted service life. The guide bar and drive bar, attached on the underside, can also create a problem because, along the deflection rollers, these parts are also subjected to heavy stress even in case of divided deflection rollers. Another disadvantage has to do with the relatively high price for the equipment of belt bands with such guide bars and the danger that the guide bar might be separated from the belt. On the other hand, of course, it is advantageous that these guide bars create the possibility of guiding such bands around curves so that considerably larger conveyor belt lengths can thus be achieved.
The task of the invention is to create a belt conveyor that is to be guided around curves also having a tight radius and whose belt band is kept clear and free of the disadvantageous tumbling work of carrying rollers and to ensure a long service life.